Low-k dielectrics are those having a smaller dielectric constant (which represents the ratio of the permittivity of a material divided by permittivity of vacuum) relative to silicon dioxide (SiO2), which has a dielectric constant of 3.9. They can be useful as, e.g. intermetal dielectrics, IMDs, and as interlayer dielectrics, ILDs
In digital circuits, dielectrics separate conducting components (e.g., wire interconnects and transistors) from one another. As the size of circuit elements becomes smaller, semiconductor components have scaled, and so have dielectrics. With scaling, resistance capacitance (RC) delay time has increasingly dominated circuit performance. In some circumstances, dielectrics have thinned to the point where, e.g., charge build up and crosstalk adversely affect the performance of semiconductor devices. By replacing traditional dielectrics such as silicon dioxide with low-k dielectrics, RC delay/parasitic capacitance can be reduced, thereby enabling faster switching speeds and lower heat dissipation. Thus, in the semiconductor fabrication industry, there has been an interest in incorporating low-k dielectric materials into semiconductors as a strategy to allow for continued scaling of microelectronic devices.
However, low-k dielectrics can present problems during downstream processing. For example, integrating low-k dielectrics successfully into a reliable CMOS device manufacturing process proves to be extremely difficult due to the dielectric film having low resistance to the downstream process-induced damage (including, e.g., polishing, wet processes, ashing, etching, and preclean plasma damage during, e.g., copper diffusion barrier deposition).
Thus, a need exists for improved methods of forming semiconductor devices incorporating low-k dielectric films that can better withstand downstream processing.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was, at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.